Documents / Document
This is the final highway accident report (NTSB-HAR-71-1) from the National Transportation Safety Board, adopted in December 1970. It covers the collapse of the U.S. 35 bridge between Point Pleasant, West Virginia, and Kanauga, Ohio, on December 15, 1967, which killed 46 people. The Board found that the cause was a cleavage fracture in eyebar 330 at joint C13N. That fracture grew from a flaw produced over 40 years by stress corrosion and corrosion fatigue, in a spot that could not be seen or found by inspection.
“Cooper”1 page
Read from the scan by GLM-OCR; expect the odd misread word.
loading. In both cases, the experimentally determined stress concentration factors were high enough to indicate yielding at the edge of the hole under the action of dead load stress alone. It is therefore likely that the material at this location was cold worked by having been strained well in excess of the yield strain sometime during the life of the structure, with subsequent "elastic" behavior up to this level and an increased susceptibility to either stress-corrosion or corrosion fatigue. The work of the Battelle laboratory confirms that there were substantial differences in residual stress between the two faces of the bar.
The range of stress at the edge of the hole was probably governed by a stress concentration factor essentially that of the elastic case, 2.77. As discussed in Reference 2, the load history of the bridge is not sufficiently well established to compute the number of cycles of various percentages of full live load stress. The typical loading conditions to produce various percentages of full live load stress in the north chain are as follows:
100% Design stress - both lanes, maximum load full length of bridge
75% Design load - north lane, maximum load full length of bridge
50% Design load - both lanes, maximum load west end to center
37-1/2% Design load - north lane, maximum load west end to center 20% Design stress - north lane, mixed truck and auto loads, west end to center
40% Design stress - Actual load at time of collapse
The interim report (Reference 2) showed that the typical traffic in 1964 was a mixture containing only about 16 percent heavy vehicles. Significant percentages of full live load design stress could therefore have been produced only when traffic was halted and vehicles bunched to the extent that actual loadings approached the design load. Under these conditions, the dynamic effects of live load are probably negligible. It would appear reasonable to assume that the loading at the time of collapse was an upper bound to the peak live load which might have occurred on the structure not more than 20 and 30 times per day, or roughly 300,000 to 450,000 times during the 40 year life of the structure. The stress range would be about 2.77 x 5,000 psi. or 13,350 psi. An ordinary fatigue failure is therefore not likely, since a fatigue life of at least $ 1 \times 1 0^{9} $ cycles is indicated for such a stress range.
## C. The Mechanism of Collapse as Determined by the Process of Elimination
Referring again to the logic diagram of Figure 3, it is apparent that all but one possible path in this diagram has been eliminated. The items not previously eliminated at the first level are (1) dynamic Document, cited by the archive. The PDF is mirrored here; the original link is above. The text was read from the page images by GLM-OCR; expect the odd misread word. 202 pages are in the text index: search them above, or from the library's search.